IEEE C802.16m-09/0196

Project / IEEE 802.16 Broadband Wireless Access Working Group <
Title / Comments on SDD fordefining ARQ feedback triggering conditions
Date Submitted / 2009-01-05
Source(s) / Youngbin Chang, Anil Agiwal, Baowei Ji, Rakesh Taori, Jungje Son
Samsung Electronics / ,

Re: / Call for Comments on 802.16m SDD (IEEE 802.16m-08/052)
Abstract / This contribution is about ARQ feedback triggering conditions
Purpose / For adopting proposed text into 16m SDD
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Comments on SDD for defining ARQ feedback triggering conditions

Youngbin Chang, Anil Agiwal, Baowei Ji, Rakesh Taori, Jungje Son

Samsung Electronics

1Problem description

In current 16e standard, ARQ feedback triggering condition in the receiver side is not defined. This causes several problems,

-Many ARQ feedback types: To support various error patterns, many ARQ feedback types are needed.

  • Cumulative ACK: if there is no error in the receiver.
  • Selective ACK: if error pattern is selective.
  • Block sequence ACK : if error pattern is contiguous
  • Cumulative + Selective or Block sequence: if some data received correctly and some data has an error (Depending on error pattern)

-Receiver complexity problem: Receiver should have own ARQ feedback triggering algorithm depending on error pattern analysis.

-Transmitter can not control the frequency of ARQ feedback

  • If receiver sends ARQ feedback frequently, it causes redundant air signaling
  • If receiver sends ARQ feedback rarely, it causes ARQ window stalling and ARQ retransmission delay

2Reason for defining ARQ triggering conditions

Desirable for the transmitter to have a control on ARQ feedbacks.

-Transmitter can receive ARQ feedback in a predictable manner.

-Transmitter should be able to request ARQ feedback if it is necessary

Receiver should have ARQ feedback triggering conditions

-Reduce receiver complexity –define explicit conditions when ARQ feedback shall be sent.

-Simplifying ARQ feedback type: triggering condition can prevent various ARQ error patterns.

  • Block sequence ACK (long contiguous NAK patterns does not happen) does not need if ARQ feedback is triggered when missed ARQ block is detected in the receiver side.

3Proposed triggering conditions

Transmitter side

-ARQ feedback polling in a transmitter side

  • To avoid ARQ window stalling
  • Transmitter can update latest ARQ reception information from the receiver when it is necessary.

Receiver side

-Receiver detects a missing ARQ block, ARQ feedback is triggered.

  • Fast ARQ retransmission is possible.
  • Remove long contiguous NAK patterns
  • HARQ re-ordering time should be considered when detecting missing ARQ block

-Receiver receives a fixed number of ARQ blocks, ARQ feedback is triggered

  • Transmitter does not need to poll if receiver sends ARQ feedback properly.
  • The fixed number of ARQ blocks is a negotiation parameter during connection setup

-New ARQ block does not arrive at the receiver during predetermined time, ARQ feedback is triggered

  • If a last transmitted ARQ block is missed, then receiver can not detect ARQ block SN missing

4Text Proposal

[Insert the following text after line 9 on page 42:]

Transmitter can request ARQ feedback from the receiver, to update the reception status of the transmitted ARQ blocks.Receiver sends an ARQ feedback when one of the following conditions is met:

- ARQ feedback request is received from the transmitter

- An ARQ block has been missing for a predetermined period

- Fixed number of ARQ blocks is correctly received

- New ARQ block is not received during a predetermined period